Wireless charging systems having an off-transducer and on-vehicle transducer that are magnetically coupled and transfer electrical energy wirelessly across a physical gap are well known. Due to the various loading, tolerances of components, temperature, the resonant frequency for optimal magnetic coupling between off-transducer and on-vehicle transducer the can vary. To maintain the highest level of efficiency there needs to be a way to operate the charging system to maintain optimal magnetic coupling of the system. In addition, interoperability of the wireless charging system with on-vehicle transducers built by different vendors that have different resonant frequencies need to be addressed to that each vendor's on-vehicle transducer does not need to be used only with that vendor's wireless charging system.